Retinol-binding protein catabolism

Two independent families have been described in the literature that have abnormally low blood RBP-ROH levels [114-117]. In one family from Japan, several members reportedly have serum RBP-ROH levels that are approximately 50% that of normal [114-116]. These diminished RBP-ROH levels did not respond to oral administration of retinol or to a protein-rich diet [114-116]. RBP isolated from one affected member of this family demonstrated no differences in its molecular weight, isoelectric point, binding to TTR or immunological properties as compared to RBP isolated from unaffected family members [114-116]. At present it is not clear whether the diminished RBP-ROH levels measured in these individuals arises from some defect in the gene for RBP or if the defect exists in another gene that has an important influence on the normal physiology of RBP-ROH (i.e. on RBP synthesis, secretion, turnover or catabolism). 

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